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Endangered bumblebees to be counted and studied this summer

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CHAMPAIGN, Ill., 5/31/18: Researchers at the Illinois Natural History Survey (INHS) are hoping to find colonies of the federally endangered rusty patched bumblebee, once active in Illinois and now on the brink of extinction. By studying the insects’ behavior and habitats, they can determine ways to stop population declines.

Handling endangered species is illegal, but Jason Robinson, INHS entomologist, received a permit from the U.S. Fish and Wildlife Service (USFWS) to inventory and study bees this summer. Botanists at the survey have also been studying bee habitats during the past year.

“With the multidisciplinary research at the INHS, we’re best suited and have the best resources to contribute to the conservation of this insect,” Robinson said.

With hand-held nets, the scientists sweep bees from various areas to determine the species they find. With the USFWS protocol on capturing and counting bees, Robinson plans to scientifically evaluate the method to learn if different kinds of vegetation cover alter the probability of detecting the bee.

Robinson will mark bees to determine if they have been recaptured during surveys, which is information vital to determining the population size at a site.

The population of this particular species dropped dramatically over the past 20 years. Small, scattered populations occur in only 13 states.

“There are very few recent records of the rusty patched bumblebees,” Robinson said. “In Illinois, there are still some populations in the northern one-third of the state. We’re not clear why this is.”

Researchers believe that bumblebee numbers have declined because of loss of habitat, particularly prairie and grassland, diseases, pesticides that kill bumblebees, and other factors. Bumblebees are pollinators whose role is necessary for reproduction of various plants.

Although bumblebee colonies may contain thousands of bees in summer, each new colony in the spring was started by one queen bee. She is vulnerable to any number of threats.

Extinction vortex may also contribute to population declines. As genetic diversity decreases when mated pairs of bees are too closely related, male bumblebees can become sterile. Scientists don’t know that this is the case, but study of the bumblebees will shed more light on the problem.

The rusty patched bumblebee is the first bumblebee to be declared endangered.